a cube reminding a black box is put into a large industry hall. at the top of the cube there is a spyhole which makes the visitor look at an arrangement of sleeping angels. this arrangement is being placed 11 meters below the floor on which the spectator is standing. most of the spectators don’t believe they are looking so deep. maybe subconciously they seem to prefer to believe they are being presented an optical illusion on a solid floor, rather then knowing the truth, that there may be some gap where they wouldn’t expect it to be.